This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Chronic Obstructive Pulmonary Disease (COPD) is currently as the 4th leading cause of death in the United States, and is expected to rise to #3 worldwide by the year 2020. This disease can cause destruction of lung tissue, inflammation of the airways in the lungs, as well as increased cough, shortness of breath and limitation of daily activities. Because of impairment in gas exchange in the lungs, many persons with COPD require supplementary oxygen supply to maintain adequate blood oxygen levels. Current guidelines recommend prescribing supplementary oxygen for patients with oxygen saturation levels of 88% or less. Such oxygen administration has been shown to be of benefit in improved survival rates, as well as increased ability to perform activities of daily living. The Long-term Oxygen Treatment Trial (LOTT) is a National Institutes of Health sponsored multi-center, randomized clinical trial of continuous (24-hour) supplemental oxygen therapy versus no supplemental oxygen therapy for patients with COPD and a moderately low resting blood oxygen level. The trial primary goal is to determine if continuous supplemental oxygen therapy results in improved survival. High priority secondary outcomes are disease-specific quality of life (St. George s Respiratory Questionnaire) and a more general health-related quality of life (Quality of Well-Being Scale). The study will also look at the rate of COPD flare-ups, degree of shortness of breath, six-minute walk distance, nutritional status and health care utilization. Other areas to be examined include breathing test results, general quality of life, sleep quality, and depression and anxiety symptoms.